Conventionally, an art that an obstacle detection sensor detecting an obstacle is provided in an unmanned traveling vehicle, a standard value is extended at the time of high speed traveling of the traveling vehicle so as to prevent a minor collision beforehand even when a stop distance from detecting the obstacle is extended, and the standard value is shortened at the time of low speed traveling such as turning so as not to detect a standing tree and the like around the turning is known (for example, see the Patent Literature 1).